The upshot of my work (and a similar study by Stuart Soroka and Chris Wlezien) is that the majority of wealthier Americans usually want the same thing out of government as the majority of poorer Americans. So, it is usually impossible to represent the rich without representing the poor. Bartels's pithy "Homer Gets a Tax Cut" actually offers some explanations for why this may be the case by examining the case of support for President Bush's 2001 tax cut proposal across income groups---including among the poor who did not stand to gain much directly from the proposal. Whatever the cause, though, representational bias can only emerge if majorities of rich people and poor people are on different sides of the issue, which is rarely the case. Income is just not the pivotal social cleavage in American politics often enough for this systematic bias to emerge.
This leaves a puzzle. How do we account for the evidence presented by Bartels and Gilens. Jim Stimson suggests an answer: measurement error. Since income is positively associated with political sophistication, wealthier Americans are more apt to understand politics in the terms used by pollsters and other political elites and to express their ideological orientations and attitudes more precisely in survey responses than poorer Americans. This creates an unfair horse race between the aggregated preferences of wealthier and poorer citizens in models of legislative voting and policy outcomes. These models include two indicators of the same thing: public opinion. One of those indicators has much more measurement error than the other. As a result:
[T]o the degree that upper-income constituents are also better educated, more involved, and so forth, we would expect their views to be the most precise, with those of the middle less so, and those of the lower-income constituents least. This would produce the reported finding, even in the absence of any discriminatory behavior on the part of senators.I am sympathetic to the idea that public policy can influence the distribution of income, but I don't think the growth of income inequality follows from a bias in the system of representation. To the extent that that growing skewness in income is the result of political choices rather than structural changes in the economy (e.g. globalization putting downward pressure on manufacturing wages and upward pressure on "superstar" wages in finance) it has emerged, in part, because lower income Americans have joined with higher income Americans in their opposition to high taxation wealthy Americans. Understanding how poor, working class, and middle class Americans link (or do not link) their economic self-interest with their political preferences and behaviors is a more promising path for sorting out the inequality problem than simply blaming a selectively unresponsive government.